(1) Field of the Invention
The present invention relates to a linear compressor in which a cylinder slidably supporting a piston is supported in a hermetic vessel by a coil spring.
(2) Description of the Prior Art
In refrigeration cycle, it is said that HCFC-based refrigerants such as R22 are stable compounds and decompose the ozone layer. In recent years, HFC-based refrigerants begin to be utilize as alternative refrigerants of HCFCs, but these HFC-based refrigerants have the nature for facilitating the global warming. Therefore, people start employing HC-based refrigerants which do not decompose the ozone layer or largely affect the global warming.
However, since this HC-based refrigerant is flammable, it is necessary to prevent explosion or ignition so as to ensure the safety. For this purpose, it is required to reduce the amount of refrigerant to be used. On the other hand, the HC-based refrigerant itself does not have lubricity and is easily melted into lubricant. For these reasons, when the HC-based refrigerant is used, an oilless or oil pure compressor is required, and a linear compressor in which almost no load is applied in a direction perpendicular to an axis of its piston is effective.
In the case of the linear compressor, since a compressing mechanism vibrates, it is necessary to prevent the vibration from being transmitted outside.
Further, the linear compressor is known as a compressor of a type in which oilless can be realized easier as compared with a reciprocating compressor, a rotary compressor and a scroll compressor.
However, even in this linear compressor, there exist sliding surfaces between its cylinder and piston, the sliding performance between the sliding surfaces has a great effect on both efficiency and durability of the linear compressor. Therefore, in order to make the linear compressor into an oilless compressor, very complicated design is required.